Method, apparatus, and computer program product for location based query for interferer discovery in coexistence management system

ABSTRACT

Method, apparatus, and computer program product embodiments are disclosed for managing coexistence of secondary users in RF spectrum. An example embodiment includes receiving, by a coexistence manager, information indicating that a candidate wireless network served by another coexistence manager may interfere with a wireless network served by the coexistence manager; determining a location related to the wireless network served by the coexistence manager; transmitting a request message to the other coexistence manager, indicating the location and requesting an estimate of a transmission signal level at the location caused by the candidate wireless network; receiving from the other coexistence manager, a response message including information indicating an estimated transmission signal level at the location caused by the candidate wireless network; and determining whether the candidate wireless network interferes with the wireless network served by the coexistence manager based on the received estimated transmission signal level.

FIELD

The field of the invention relates to efficient radio spectrum use, andmore particularly to managing coexistence of secondary users in RFspectrum.

BACKGROUND

Use of radio frequency bands of the electromagnetic spectrum isregulated by governments in most countries, by allocating specificfrequency bands to particular types of uses, such as licensed bands forcommercial radio and television broadcasting, cellular telephony, mobilenetworks such as CDMA2000, WCDMA, HSPA, LTE, and IMT, maritime radio,police, fire, and public safety radio, GPS, radio astronomy, earthstations for satellite communications, and many other uses. Governmentsalso allocate unlicensed bands, for example, for Wireless Regional AreaNetwork (WRAN) broadband access for rural areas and wireless local areanetworks (WLAN) and wireless personal area networks (WPAN), such as theindustrial, scientific, and medical (ISM) band.

In the United States, the Federal Communications Commission (FCC)regulates use of the radio spectrum, including radio and televisionbroadcasting. Frequencies are allocated according to a bandplan in whichguard bands are assigned between the allocated radio bands to avoidinterference between adjacent signals. There are also unassignedfrequency bands in the spectrum that either have never been used or havebecome free as a result of changes in technology. Unassigned or un-usedfrequencies also appear locally inside the frequency bands, which areotherwise allocated in other locations. The unassigned frequency bandsand guard bands are referred to as white spaces.

TV white space may be broadly defined as broadcast television spectrumthat is unused by licensed services. There are at least two categoriesof TV white space: [1] Dedicated TV white space is a portion of thespectrum that the FCC has reallocated to unlicensed use from previouslyanalog broadcast usage, and [2] Locally unused spectrum by licensed TVbroadcasters in a geographic area.

[1] Dedicated TV white space: In the United States, the FCC hasdedicated approximately 400 MHz of white spaces for unlicensed use thatbecame unused after a federally mandated transformation of analog TVbroadcasting to digital TV broadcasting. However, the FCC has prohibitedunlicensed use of white spaces from interfering with existing licenseduses, including digital TV stations, low power TV stations, cable TVheadends, and sites where low power wireless microphones are used.Various proposals have been made for unlicensed use of the white spacesleft by the termination of analog TV, for example rural broadbanddeployment, auxiliary public safety communications, educational andenterprise video conferencing, personal consumer applications, meshnetworks, security applications, municipal broadband access, enhancedlocal coverage and communications, fixed backhaul, and sensoraggregation for smart grid meter reading.

[2] Locally unused spectrum by licensed TV broadcasters: The FCC hasadopted rules to allow unlicensed radio transmitters to operate in thebroadcast television spectrum at locations where that spectrum is notbeing used by licensed broadcasters. The FCC proposes two mechanisms toenable the unlicensed transmitter to discover the available channels:geo-location and database based approach, and spectrum sensing. The useof one of the mechanisms is required for the unlicensed transmitter. TheFCC proposed the use of geolocation to establish the location of theunlicensed transmitter and a database of TV bands use by licensedbroadcasters organized by their geographic coverage areas, to enable theunlicensed transmitter to know where local TV band white spaces may beavailable. The FCC proposed the use of spectrum sensors in theunlicensed transmitter to detect the presence of the incumbent, primaryTV broadcaster's signal in the local TV band to enable the unlicensedtransmitter to immediately relinquish using the band. A primary user insuch a local TV band would be an incumbent TV broadcaster licensed tooperate in that band, but in those geographic areas where there are nolicensed incumbent TV broadcasters in operation, other unlicensedsecondary users may make use of that band. There may be also otherincumbent users in the TV band, which the secondary users should avoid,such as program making and special events (PMSE) systems.

In addition to the United States, other countries are also consideringto enable unlicensed, secondary operation in TV band white spaces. Therequirements may slightly differ in different countries, e.g. in theUnited States the maximum transmit power for unlicensed device isdefined based on the device type, whereas in Europe location specificmaximum transmission power has been considered. In that case the maximumallowed transmission power for an unlicensed device would depend on thedevice geo-location, i.e. the distance from the primary users. Thedevice characteristics, such as emission mask/ACLR (adjacent channelleakage ratio) may affect the maximum allowed transmission power.

Other RF spectrum white spaces may be defined as RF spectrum that islocally unused in certain geographic areas, such as for examplefrequency allocations from maritime radio in landlocked areas remotefrom the sea. A primary user in such a maritime radio band would be amaritime radio licensed to operate in that band, but in those geographicareas where there are no licensed maritime radios in operation, otherunlicensed secondary users may make use of that band. Similarly, locallyunused spectrum white spaces may be present in certain geographiclocations, such as the frequency allocations from 2.025 GHz to 2.110 GHzfor earth stations to transmit to communications satellites, in areasremote from such earth stations. A primary user in such a satelliteearth station radio band would be a satellite earth station licensed tooperate in that band, but in those geographic areas where there are nosatellite earth stations in operation, other unlicensed secondary usersmay make use of that band. Further, other schemes of secondary use ofspectrum, other than unlicensed schemes may exist, such as licensing,regulator defined policies, cognitive principles, or authorized sharedaccess.

SUMMARY

Method, apparatus, and computer program product embodiments aredisclosed for managing coexistence of secondary users in RF spectrum.

An example embodiment of the invention includes a method comprising:

receiving, by a coexistence manager, information indicating that acandidate wireless network served by another coexistence manager mayinterfere with a wireless network served by the coexistence manager;

determining, by the coexistence manager, at least one location relatedto the wireless network served by the coexistence manager;

transmitting, by the coexistence manager, a request message to the othercoexistence manager, indicating the at least the one location andrequesting an estimate of a transmission signal level at the at leastone location caused by the candidate wireless network;

receiving, by the coexistence manager, from the other coexistencemanager, a response message including information indicating anestimated transmission signal level at the at least one location causedby the candidate wireless network; and

determining, by the coexistence manager, whether the candidate wirelessnetwork interferes with the wireless network served by the coexistencemanager based on the received estimated transmission signal level at theat least one location.

An example embodiment of the invention includes a method comprising:

wherein the information indicating that the candidate wireless networkmay interfere with the wireless network served by the coexistencemanager is received from a coexistence discovery and information server.

An example embodiment of the invention includes a method comprising:

performing, by the coexistence manager, calculations using the receivedestimated transmission signal level, to estimate an effect of thereceived estimated transmission signal level on the wireless networkserved by the coexistence manager; and

determining, by the coexistence manager, to include the candidatewireless network in a coexistence set based on the performedcalculations.

An example embodiment of the invention includes a method comprising:

wherein the at least one location related to the wireless network servedby the coexistence manager, is one of actual location or estimatedlocation of one or more apparatuses belonging to the wireless network.

An example embodiment of the invention includes a method comprising:

wherein the request message includes at least one of an identificationof the wireless network served by the coexistence manager, andfrequencies at which the wireless network served by the coexistencemanager, is capable of operating.

An example embodiment of the invention includes a method comprising:

wherein locations indicated in the request cover locations of a masterdevice and most probable locations of slave devices in the wirelessnetwork served by the coexistence manager.

An example embodiment of the invention includes an apparatus comprising:

at least one processor;

at least one memory including computer program code;

the at least one memory and the computer program code configured to,with the at least one processor, cause the apparatus at least to:

receive information indicating that a candidate wireless network servedby another coexistence manager may interfere with a wireless networkserved by the apparatus;

determine at least one location related to the wireless network servedby the apparatus;

transmit a request message to the other coexistence manager, indicatingthe at least the one location and requesting an estimate of atransmission signal level at the at least one location caused by thecandidate wireless network;

receive from the other coexistence manager, a response message includinginformation indicating an estimated transmission signal level at the atleast one location caused by the candidate wireless network; and

determine whether the candidate wireless network interferes with thewireless network served by the apparatus, based on the receivedestimated transmission signal level at the at least one location.

An example embodiment of the invention includes an apparatus comprising:

wherein the information indicating that the candidate wireless networkmay interfere with the wireless network served by the coexistencemanager is received from a coexistence discovery and information server.

An example embodiment of the invention includes an apparatus comprising:

the at least one memory and the computer program code configured to,with the at least one processor, cause the apparatus at least to:

perform calculations using the received estimated transmission signallevel, to estimate an effect of the received estimated transmissionsignal level on the wireless network served by the coexistence manager;and

determine to include the candidate wireless network in a coexistence setbased on the performed calculations.

An example embodiment of the invention includes an apparatus comprising:

wherein the at least one location related to the wireless network servedby the coexistence manager, is one of actual location or estimatedlocation of one or more apparatuses belonging to the wireless network.

An example embodiment of the invention includes an apparatus comprising:

wherein the request message includes at least one of an identificationof the wireless network served by the coexistence manager, andfrequencies at which the wireless network served by the coexistencemanager, is capable of operating.

An example embodiment of the invention includes an apparatus comprising:

wherein locations indicated in the request cover locations of a masterdevice and most probable locations of slave devices in the wirelessnetwork served by the coexistence manager.

An example embodiment of the invention includes a computer programproduct comprising computer executable program code recorded on acomputer readable, non-transitory storage medium, the computerexecutable program code comprising:

code for receiving, by a coexistence manager, information indicatingthat a candidate wireless network served by another coexistence managermay interfere with a wireless network served by the coexistence manager;

code for determining, by the coexistence manager, at least one locationrelated to the wireless network served by the coexistence manager;

code for transmitting, by the coexistence manager, a request message tothe other coexistence manager, indicating the at least the one locationand requesting an estimate of a transmission signal level at the atleast one location caused by the candidate wireless network;

code for receiving, by the coexistence manager, from the othercoexistence manager, a response message including information indicatingan estimated transmission signal level at the at least one locationcaused by the candidate wireless network; and

code for determining, by the coexistence manager, whether the candidatewireless network interferes with the wireless network served by thecoexistence manager based on the received estimated transmission signallevel at the at least one location.

An example embodiment of the invention includes a method comprising:

receiving, by a coexistence manager, a request message from anothercoexistence manager, indicating at least one location related to anotherwireless network served by the other coexistence manager and requestingan estimate of a transmission signal level at the at least one location,caused by a candidate wireless network served by the coexistencemanager;

estimating, by the coexistence manager, a transmission signal level atthe at least one location, caused by the candidate wireless networkserved by the coexistence manager; and

transmitting, by the coexistence manager, a response message includinginformation indicating the estimated transmission signal level at the atleast one location.

An example embodiment of the invention includes a method comprising:

wherein the request message includes one or more of frequencies at whichthe coexistence manager is requested to estimate the transmission signallevel.

An example embodiment of the invention includes an apparatus,comprising:

at least one memory including computer program code;

the at least one memory and the computer program code configured to,with the at least one processor, cause the apparatus at least to:

receive a request message from another coexistence manager, indicatingat least one location related to another wireless network served by theother coexistence manager and requesting an estimate of a transmissionsignal level at the at least one location related to the other wirelessnetwork, caused by a candidate wireless network served by the apparatus;

estimate a transmission signal level at the at least one locationrelated to the other wireless network, caused by the candidate wirelessnetwork; and

transmit a response message including information indicating theestimated transmission signal level at the at least one location.

An example embodiment of the invention includes an apparatus,comprising:

wherein the request message includes one or more of frequencies at whichthe coexistence manager is requested to estimate the transmission signallevel.

An example embodiment of the invention includes a computer programproduct comprising computer executable program code recorded on acomputer readable, non-transitory storage medium, the computerexecutable program code comprising:

code for receiving, by a coexistence manager, a request message fromanother coexistence manager, indicating at least one location related toanother wireless network served by the other coexistence manager andrequesting an estimate of a transmission signal level at the at leastone location related to the other wireless network, caused by acandidate wireless network served by the coexistence manager;

code for estimating, by the coexistence manager, a transmission signallevel at the at least one location related to the other wirelessnetwork, caused by the candidate wireless network; and

code for transmitting, by the coexistence manager, a response messageincluding information indicating the estimated transmission signal levelat the at least one location.

The example embodiments of the invention manage coexistence of secondaryusers in RF spectrum.

DESCRIPTION OF THE FIGURES

FIG. 1A is a system architecture diagram according to an exampleembodiment of the invention, illustrating three network controllers orcoexistence managers CM_A, CM_B, and CM_C, each managing resourceallocations of white space spectrum for a respective wireless networksor white space objects (WSOs) A1, B1, and C1/C2. The WSOs B1 and C1 arein the coexistence set for WSO A1. The requesting coexistence managerCM_A has received information from the coexistence discovery andinformation server (CDIS) indicating that WSO C2 is a candidate forinclusion in the coexistence set for WSO A1. The requesting coexistencemanager CM_A determines at least one location (X,Y) related to WSO A1.The requesting coexistence manager CM_A transmits a request message toCM_C requesting an estimate of the signal level for at least onelocation (X,Y) of WSO A1, caused by WSO C2, in an example embodiment ofthe invention.

FIG. 1B illustrates the system architecture diagram of FIG. 1A, showingthe responding coexistence manager CM_C responding to the request byestimating the signal level for at least one location (X,Y) of WSO A1,caused by WSO C2. The responding coexistence manager CM_C transmits aresponse message to the requesting coexistence manager, including theestimated signal level for at least one location (X,Y) of WSO A1, causedby WSO C2, in an example embodiment of the invention.

FIG. 1C illustrates the system architecture diagram of FIG. 1B, showingthe requesting coexistence manager CM_A determining from the estimatedsignal level, if the WSO C2 is in the coexistence set of WSO A1. In theexample shown, the estimated transmission signal level at the at leastone location (X,Y) of WSO A1, is sufficiently high to justify includingWSO C2 in the coexistence set of WSO A1, in an example embodiment of theinvention.

FIG. 1D is an example system architecture according to an exampleembodiment of the invention, showing two of the network controllers CM_Aand CM_C of FIG. 1A serving the respective wireless networks A1 andC1/C2, in an example embodiment of the invention.

FIG. 1E is an example network diagram according to an example embodimentof the invention, showing a simplified depiction of the coexistence setA of wireless networks B1 and C1 that are neighbors to the wirelessnetwork A1, wherein the three network controllers CM_A, CM_B, and CM_C,each manage resource allocations of white space spectrum for arespective one or more wireless networks A1, B1, and C1/C2, in anexample embodiment of the invention.

FIG. 2A is an example system architecture according to an exampleembodiment of the invention of FIG. 1A, which illustrates the requestingnetwork controller or coexistence manager CM_A, accessing thecoexistence discovery and information server (CDIS) in FIG. 1A, toobtain the addresses of potential neighbor networks and receiving theaddresses of the neighbor coexistence managers CM_B and CM_C. Therequesting coexistence manager CM_A receives information indicating WSOC2 is a candidate for inclusion in the coexistence set for WSO A1, in anexample embodiment of the invention.

FIG. 2B is an example system architecture according to an exampleembodiment of the invention of FIG. 2A, which illustrates the requestingcoexistence manager CM_A determining at least one location (X,Y) relatedto WSO A1. The requesting coexistence manager CM_A transmits a requestmessage to CM_C requesting an estimate of the signal level for at leastone location (X,Y) of WSO A1, caused by WSO C2, in an example embodimentof the invention.

FIG. 2C is an example system architecture according to an exampleembodiment of the invention of FIG. 2A, which illustrates the respondingcoexistence manager CM_C responding to the request by estimating thesignal level for at least one location (X,Y) of WSO A1, caused by WSO C2and transmitting a response message to the requesting coexistencemanager, including the estimated signal level for at least one location(X,Y) of WSO A1, caused by WSO C2. The requesting coexistence managerCM_A determines from the estimated signal level, if the WSO C2 is in thecoexistence set of WSO A1. In the example shown, the estimatedtransmission signal level at the at least one location (X,Y) of WSO A1,is sufficiently high to justify including WSO C2 in the coexistence setof WSO A1, in an example embodiment of the invention.

FIG. 3A is an example network diagram of the WSO A1, illustrating thatthe at least one location (X,Y) related to WSO A1 may be the actuallocation, where WSO A1 is a single transceiver in one location and therequesting coexistence manager CM_A is permitted to release the WSO'slocation to another coexistence manager. Alternately, the requestingcoexistence manager CM_A may indicate a set of locations, one of whichmay be the actual location of the WSO A1, in an example embodiment ofthe invention.

FIG. 3B is an example network diagram of the WSO A1 as a networkcomprising a master device and several slave devices, illustrating thatthe at least one location (X,Y) related to WSO A1 may be an average ofall of the locations of the devices in the network, in an exampleembodiment of the invention.

FIG. 4A is an example network diagram of the WSO C2, illustrating thatWSO C2 is a single transceiver WSD3 in one location, then the respondingcoexistence manager CM_C estimates the signal level for at least onelocation (X,Y) of WSO A1, caused by the single transceiver WSD3, in anexample embodiment of the invention.

FIG. 4B is an example network diagram of the WSO C2, illustrating thatWSO C2 is a network comprising a master device WSD3 and several slavedevices including slave device WSD4, then the responding coexistencemanager CM_C estimates the maximum signal level for at least onelocation (X,Y) of WSO A1, caused by the devices (actual or estimatedones) in the network of WSO C2, in an example embodiment of theinvention.

FIG. 5 is a non-limiting example frequency band diagram illustrating anexample TDMA coexistence frame sub-band in the TV band white spacelocally unused by licensed TV broadcasters, representing broadcast TVchannels in the Richmond, Va. (USA) area, as shown in FIG. 6, an exampleTDMA coexistence frame a in sub-band in the FCC dedicated TV band whitespace, and an example TDMA coexistence frame in a sub-band in the earthstation-to-satellite locally unused white space spectrum, according toan embodiment of the present invention.

FIG. 6 is an example map of the Richmond, Va. (USA) geographic area andan overlay of coverage areas for broadcast TV channels, illustratingthat there is a locally available TV band white space that is unused bylicensed TV broadcasters, according to an embodiment of the presentinvention.

FIG. 7A is a functional block diagram according to an example embodimentof the invention, illustrating an example master WSD9 device includingthe control node or coexistence enabler for the wireless device. Thedevice may be configured to operate in the TVWS coexistence bands oradditional RF spectrum white space spectrum where there may be noprimary user radios operating in the neighboring wireless networks, inan example embodiment of the invention.

FIG. 7B is a functional block diagram according to an example embodimentof the invention, illustrating an example slave WSD10 device includingthe control node or coexistence enabler for the wireless device. Thedevice may be configured to operate in the TVWS coexistence bands oradditional RF spectrum white space spectrum there may be no primary userradios operating in the neighboring wireless networks, in an exampleembodiment of the invention.

FIG. 7C is an example network diagram according to an embodiment of thepresent invention, illustrating the control node or coexistence enabler,communicating over a backhaul wireline and/or internet link with thenetwork controller or coexistence manager, in an example embodiment ofthe invention.

FIG. 8A is an example flow diagram 600 of operational steps inrequesting coexistence manager CM_A, according to an embodiment of thepresent invention.

FIG. 8B is an example flow diagram 650 of operational steps inresponding coexistence manager CM_C, according to an embodiment of thepresent invention.

FIG. 9 is an example frequency band diagram illustrating an example TDMAcoexistence frame in a sub-band in an unpaired time domain duplexfrequency white space in the uplink portion of a mobile devicecommunications frequency band, according to an example embodiment of theinvention.

FIG. 10 illustrates an example embodiment of the invention, whereinexamples of removable storage media are shown, based on magnetic,electronic and/or optical technologies, such as magnetic disks, opticaldisks, semiconductor memory circuit devices and micro-SD memory cards(SD refers to the Secure Digital standard) for storing data and/orcomputer program code as an example computer program product, inaccordance with at least one embodiment of the present invention.

DISCUSSION OF EXAMPLE EMBODIMENTS OF THE INVENTION

In the United States, the FCC has opened up 300 MHz to 400 MHz of whitespaces for unlicensed use that became unused after a federally mandatedtransformation of analog TV broadcasting to digital TV broadcasting.However, the FCC has prohibited unlicensed use of white spaces frominterfering with existing licensed uses, including digital TV stations,low power TV stations, cable TV headends, and sites where low powerwireless microphones are used.

The FCC has defined the regulation of white spaces in Second MemorandumOpinion and Order, FCC 10-174, Sep. 23, 2010 for secondary white spacedevices (WSD). In Europe, the European Conference of Postal andTelecommunications Administrations (CEPT) has defined initialrequirements in ECC Report 159: Technical and Operational Requirementsfor the Possible Operation of Cognitive Radio Systems in the ‘WhiteSpaces’ of the Frequency Band 470-790 MHz, January 2011.

Various proposals have been made for unlicensed use of the white spacesleft by the termination of analog TV, for example rural broadbanddeployment, auxiliary public safety communications, educational andenterprise video conferencing, personal consumer applications, meshnetworks, security applications, municipal broadband access, enhancedlocal coverage and communications, fixed backhaul, and sensoraggregation for smart grid meter reading.

Coexistence standards are currently being developed to enable two ormore independently operated wireless networks or devices using any radiotechnologies adapted for TV white space frequency bands, to access thesame TV white space frequency band in the same location without mutualinterference.

The IEEE 802.19 Working Group is currently defining coexistence rulesfor heterogeneous secondary networks. An example embodiment enablescoexistence between heterogeneous secondary networks. Primary networksand users are incumbent users of the selected frequency band that have aform of priority access to the band. Primary networks include networksoperating in FCC licensed bands, such as for commercial radio andtelevision broadcasting. Secondary networks and users are allowed to usethe selected band only if there are resources that are not used by theprimary users. Secondary networks include any broadband networksoperating unlicensed in the TV white spaces (TVWS) and usingtransmission devices that comply with the FCC requirements for TV BandDevices (TVBDs). Fixed TVBD devices must include geo-location and querya database to determine allowed channels. Portable master TVBD devicesmust be able to access geo-location data or include a spectrum sensingcapability to identify TV and wireless microphone signals.

The FCC has adopted rules to allow unlicensed radio transmitters tooperate in the broadcast television spectrum at locations where thatspectrum is not being used by licensed broadcasters. The FCC requiredthe use of geo-location to establish the location of the unlicensedtransmitter and a database of TV bands use by licensed broadcastersorganized by their geographic coverage areas, to enable the unlicensedtransmitter to know where local TV band white spaces may be available.Alternatively, the FCC required the use of spectrum sensors in theunlicensed transmitter to detect the presence of the incumbent, primaryTV broadcaster's signal in the local TV band white space to enable theunlicensed transmitter to immediately relinquish using the band. Aprimary user in such a local TV band white space would be an incumbentTV broadcaster licensed to operate in that band, but in those geographicareas where there are no licensed incumbent TV broadcasters inoperation, other unlicensed secondary users may make use of that band.

Other spectrum white spaces may be locally unused in certain geographicareas, such as the frequency allocations from maritime radio inlandlocked areas remote from the sea. A primary user in such a maritimeradio band would be a maritime radio licensed to operate in that band,but in those geographic areas where there are no licensed maritimeradios in operation, other unlicensed secondary users may make use ofthat band. Similarly, locally unused spectrum white spaces may bepresent in certain geographic locations, such as the frequencyallocations from 2.025 GHz to 2.110 GHz for earth stations to transmitto communications satellites, in areas remote from such earth stations.A primary user in such a satellite earth station radio band would be asatellite earth station licensed to operate in that band, but in thosegeographic areas where there are no satellite earth stations inoperation, other unlicensed secondary users may make use of that band.

Active coexistence between secondary networks using the RF white spacesmay require new techniques for fairly sharing the available bandwidthamong different heterogeneous secondary networks and accord the requiredpreference for primary users of the band. Such new techniques mayrequire some form of communication between the secondary networks toenable a fair usage of the local spectrum.

A network controller or coexistence manager (CM) is the main decisionmaker of the coexistence system proposed by the IEEE 802.19 WorkingGroup defining coexistence rules for heterogeneous secondary networks.The coexistence manager (CM) discovers and solves the coexistenceconflicts of the networks operating in the same area. A CM serves one ormore networks. Depending on the deployment, it may reside either in a TVband device (TVBD) network or device, also referred to as a white spaceobject (WSO), or in the Internet. In independent networks it may residein a TVBD. The CM discovers the interfering networks and their CMs, andshares information with other CMs. Based on the collected information itreconfigures the operation of its own networks, but also performsresource reallocation for those WSOs in a coexistence set the CM isallowed to, as needed.

In the United States, the white space device (WSD) may operate as amaster WSD of a network of associated slave WSD devices. For example,the master WSD may be an access point or base station. The master WSD isexpected to access the geo-location database (DB) on behalf of its slaveWSD devices, to discover the available spectrum that is not used by theincumbent users, for example, TV broadcasters.

A master WSD and its wireless network are registered through a controlnode or coexistence enabler (CE) to the network controller orcoexistence manager (CM). The key functions of coexistence enabler (CE)are to obtain information required for the coexistence from the WSO, andto reconfigure the WSO operation according the coexistence decisionsthat are received from the coexistence manager (CM). The collectedinformation covers the capabilities and the resource needs of the TVBDnetwork and the characteristics of the radio environment. The CE mayreside in the master WSD, such as an access point, base station, or meshpoint.

The following discussion employs terms that are defined as follows:

-   -   WSO (White Space Object)=TVBD network or device.    -   Coexistence set=neighbors.        -   Coexistence set is a set of WSOs otherwise referred to as            neighbors.        -   Each coexistence manager (CM) determines and maintains a            coexistence set for each WSO that it serves. A WSO's            coexistence set comprises of other WSOs that may interfere            the WSO or that the WSO may interfere with.        -   Interference is the effect of unwanted energy due to one or            a combination of emissions, radiations, or inductions upon            reception in a radiocommunication system, manifested by any            performance degradation, misinterpretation, or loss of            information that could be extracted in the absence of such            unwanted energy.    -   Coexistence set element=neighbor TVBD network or device        -   A WSO that belongs to a coexistence set    -   Coexistence set extension=Limiting networks (the neighbors of        neighbors)        -   Each CM has a coexistence set extension (also referred to as            an extended coexistence set) for each coexistence set it has            (one per WSO the CM serves). The extension comprises those            WSOs that belong to the coexistence sets of WSOs in one's            own coexistence set, but that do not belong to the one's own            coexistence set.

Coexistence managers (CMs) may be organized according to differentdecision making topologies for interacting and collaborating with eachother when determining resource allocations for the wireless networksand devices that they serve. The coexistence managers (CMs) may operateautonomously, they may employ centralized decision making, or they mayshare making the decisions in distributed decision making

When a system of coexistence managers (CMs) employs centralized decisionmaking, a serving CM will transfer responsibility for resourceallocation for a wireless network that it serves, to another CM,referred to herein as the master CM. As used herein, the serving CM isalso referred to as a slave CM and the wireless network that it servesis referred to as a transfer wireless network.

In an example embodiment of the invention, the serving CM has acoexistence enabler (CE) for a transfer wireless network, which isregistered with the serving CM, and the serving CM uses distributed orautonomous decision making for resource allocation for the transferwireless network. The serving CM may need to transfer responsibility forresource allocation for a wireless network that it serves, in thefollowing example circumstances:

-   -   There is one or a few CMs to which are registered most of the        coexistence enablers (CEs) of the wireless networks in the        coexistence set of the transfer wireless network;    -   The number of CMs is high, to which the coexistence set elements        of the transfer wireless network are registered; or    -   The serving CM is about to run out of resources to serve all the        CEs that are registered to it.

FIG. 1A is a system architecture diagram according to an exampleembodiment of the invention, illustrating three network controllers orcoexistence managers CM_A, CM_B, and CM_C, each managing resourceallocations of white space spectrum for a respective wireless networksor white space objects (WSOs) A1, B1, and C1/C2. The WSOs B1 and C1 arein the coexistence set for WSO A1. The requesting coexistence managerCM_A has received information from the coexistence discovery andinformation server (CDIS) indicating that WSO C2 is a candidate forinclusion in the coexistence set for WSO A1. The requesting coexistencemanager CM_A determines at least one location (X,Y) related to WSO A1.The location may also indicate the altitude, if available. The altitudemay be indicated, as an example, as the floor number in a building. Therequesting coexistence manager CM_A transmits a request message to CM_Crequesting an estimate of the signal level for at least one location(X,Y) of WSO A1, caused by WSO C2, in an example embodiment of theinvention.

In the example shown in FIG. 1A, the network controller CM_A serves onlyone wireless network A1 that operates using the IEEE 802.11 radiotechnology, the network controller CM_B serves only one wireless networkB1 that operates using the IEEE 802.11 radio technology, whereas thenetwork controller CM_C serves two wireless networks C1 and C2 thatoperate using the IEEE 802.11 radio technology.

Example white space spectrum in the operating area of a WSD deviceinclude dedicated TV white space spectrum 30, locally unused TV bands31, locally unused maritime bands 33, locally unused satellite bands 35,and locally unpaired (TDD) mobile device frequencies.

FIG. 1A also shows three non-limiting example white space spectralocally unused by licensed primary users of their respective spectrumwhite spaces, which may be used by the master WSD or slave WSD,operating as unlicensed secondary users. TV band white space 31 islocally unused by licensed TV broadcasters. Maritime radio band 33 islocally unused by licensed maritime band radios. Earthstation-to-satellite radio band 35 is locally unused by licensed earthstation radios. A non-limiting example of a TV band white space 31locally unused by licensed TV broadcasters is the 174-204 MHz band,representing the local absence of broadcast VHF TV channels 7, 8, 9, 10,and 11. If there were a local absence of licensed broadcasters in TVband white space 31, on VHF TV channels 7, 8, 9, 10, and 11, which wouldotherwise interfere with the master WSD or slave WSD, then they couldoperate as unlicensed secondary users and make use of TV band whitespace 31. If either master WSD or slave WSD were to detect a signaltransmitted from a neighboring TV broadcaster in band 31, then theywould have to relinquish their use of the TV band white space 31 andmake a resource request, in accordance with an example embodiment of theinvention. Non-limiting examples of white space spectra are available inmany parts of the electromagnetic spectrum. For example, white spacespectra are available for personal/portable devices in the UHF portionof the spectrum.

A maritime radio operates in a number of licensed frequency allocationsand is a primary user in the maritime radio band 33. If there were nolicensed maritime radios in operation that would interfere with themaster WSD or slave WSD, then they could operate as unlicensed secondaryusers and make use of maritime radio band 33. If either master WSD orslave WSD were to detect a signal transmitted from a neighboringmaritime radio, then they would have to relinquish their use of themaritime band 33 and make a resource request, in accordance with exampleembodiments of the invention.

A satellite earth station transmits to satellites in licensed frequencyallocations from 2.025 GHz to 2.110 GHz and is a primary user in theearth-to-satellite band 35. If there were no licensed earth stationradios in operation that would interfere with the master WSD or slaveWSD, then they could operate as unlicensed secondary users and make useof earth-to-satellite radio band 35. If either master WSD or slave WSDwere to detect a signal transmitted from a neighboring earth stationradio, then they would have to relinquish their use of theearth-to-satellite band 35 and make a resource request, in accordancewith example embodiments of the invention.

FIG. 1B illustrates the system architecture diagram of FIG. 1A, showingthe responding coexistence manager CM_C responding to the request byestimating the signal level for at least one location (X,Y) of WSO A1,caused by WSO C2. The responding coexistence manager CM_C transmits aresponse message 34 to the requesting coexistence manager CM_A,including the estimated signal level for at least one location (X,Y) ofWSO A1, caused by WSO C2, in an example embodiment of the invention.

FIG. 1C illustrates the system architecture diagram of FIG. 1B, showingthe requesting coexistence manager CM_A determining from the estimatedsignal level, if the WSO C2 is in the coexistence set of WSO A1. Thecoexistence set for WSO A1 comprises those other WSOs, such as WSO B1and WSO C1, that may interfere with WSO A1 or that the WSO A1 mayinterfere with. In accordance with an example embodiment of theinvention, the requesting coexistence manager CM_A may use the estimatedsignal level received in response message 34 to determine whether WSO C2may interfere with WSO A1. The estimated signal level may be indicatedas power density, power or field strength caused by WSO C2 in the atleast one location (X,Y) of WSO A1. In accordance with an exampleembodiment of the invention, the requesting coexistence manager CM_A mayperform calculations to estimate the effect of the estimated powerdensity, for example, caused by WSO C2 at the at least one location(X,Y), upon WSO A1. In an example embodiment of the invention, theestimated effect may be manifested by an estimated performancedegradation of WSO A1, an estimated misinterpretation by WSO A1, or anestimated loss of information by WSO A1 due to the estimated signallevel received in response message 34. In the example shown, theestimated transmission signal level at the at least one location (X,Y)of WSO A1, is sufficiently high to justify including WSO C2 in thecoexistence set of WSO A1, in an example embodiment of the invention.

FIG. 1D is an example system architecture according to an exampleembodiment of the invention, showing two of the network controllers CM_Aand CM_C of FIG. 1A serving the respective wireless networks A1 andC1/C2, in an example embodiment of the invention.

In an example embodiment of the invention, a network of distributedcoexistence managers CM_A and CM_C may communicate with one another overthe Internet 105. According to an example embodiment of the invention,the control node or coexistence enabler 118 in the master WSD9 may beregistered with the TVWS coexistence manager CM_A. According to analternate example embodiment of the invention, the control node orcoexistence enabler 118 in the master WSD9 may be collocated with theTVWS coexistence manager CM_A or it may be collocated with the masterWSD9 without being integrated with the master. The coexistence enabler115 in the master WSD3 may communicate over the Internet 105 with theTVWS coexistence manager CM_C. The distributed coexistence managers CM_Aand CM_C may communicate over the Internet 105, in an example embodimentof the invention. Master WSD1 may be registered through the control nodeor coexistence enabler 111 to the network controller or coexistencemanager CM_C. Master WSD3 may be registered through the control node orcoexistence enabler 115 to the network controller or coexistence managerCM_C.

In an example embodiment of the invention, the coexistence enabler 118may obtain information required for coexistence from a traffic networkor device representing it. This may include configuration and control ofmeasurements. Also, the coexistence enabler 118 may providereconfiguration commands and control information to the master WSD9,corresponding to coexistence decisions received from coexistence managerCM_A. The coexistence manager CM_A is responsible for discovery ofCoexistence Managers (CM)s CM_C managing neighboring wireless networks,for example, and coexistence related information may be exchanged withthem. The coexistence manager CM_A or CM_C may have the neededinformation to make decisions of resource sharing among the CoexistenceManagers (CM)s managing neighboring wireless networks.

The coexistence manager CM_C handles resource requests from thecoexistence enabler 111 in master WSD1. The coexistence manager CM_Ahandles resource requests from the coexistence enabler 118 in masterWSD9. The masters WSD1, WSD3, and WSD9 include IEEE 802.11 MAC and PHYto communicate over their networks. The coexistence enablers 111, 115,and 118 send resource requests to the respective coexistence managersCM_C and CM_A.

In the example system architecture of FIG. 1B the coexistence managerCM_C receives resource requests from the coexistence enabler 111 inmaster WSD1. The coexistence manager CM_C may receive Spectrum sensingresults and network parameters from the coexistence enabler 111 inmaster WSD1. Network parameters may include specific user requirements(user load, QoS, priority, etc), aggregate spectral efficiency,etiquette (first come, first served, etc.), and user or networkpolicies. The coexistence manager CM_C may access a geo-locationdatabase 200 in FIG. 1A to obtain available secondary channels in the TVband white space. The coexistence manager CM_C accesses the coexistencenetwork element coexistence discovery and information server (CDIS) 107in FIG. 1A to obtain potential neighbor networks' addresses. Thecoexistence manager CM_C processes this data in conjunction withSpectrum maps, Operational parameters, and Time base sync, to determinea resource reallocation for the coexistence enabler 111 in master WSD1.The coexistence manager CM_C then sends to the coexistence enabler 111in master WSD1 the resource reallocation, including Operationalparameters, Quiet period parameters, Spectrum sensing strategy, and/orTime base sync. The coexistence enabler 111 in master WSD1 then controlsat least one of the medium access control (MAC) and the physical layer(PHY) and the Radio resource Control (RRC) and the Radio ResourceManagement (RRM) to communicate in channels in the TV white spaces bandreallocated by the coexistence manager CM_C, without interference fromother networks sharing the same white space channels. A similaroperation may be carried out by the coexistence manager CM_A inconjunction with the coexistence enabler 118 in master WSD9. A networkof distributed coexistence managers CM_C and CM_A may communicate withone another over the Internet 105.

FIG. 1E is an example network diagram according to an example embodimentof the invention, showing a simplified depiction of the coexistence setA of wireless networks B1 and C1 that are neighbors to the wirelessnetwork A1. The three network controllers CM_A, CM_B, and CM_C, eachmanage resource allocations of white space spectrum for a respective oneor more wireless networks A1, B1, and C1/C2, in an example embodiment ofthe invention.

In accordance with an example embodiment of the invention, once a CM hasinformation about a WSO which is a potential coexistence set element fora WSO the CM serves, the CM finds out from another CM which serves thepotential coexistence set element whether the WSO the CM serves can beinterfered by the WSO which the other CM serves.

In accordance with an example embodiment of the invention, a CM iscapable of estimating transmission signal levels of WSOs that it serves,more accurately than the signal levels being indicated in the areasregistered to the CDIS. For a rough approximation in a first phase, a CMmay simply use the same propagation models that it uses to determine theareas registered to the CDIS, but in a more refined second phase, it mayat least take into account differences in transmission and antenna gainin different directions. Alternatively, the CM may use more advancedpropagation models in which it takes into account topography of theenvironment in which the WSO operates. Regardless of the model used, theCM has means to estimate transmission signal level in a set oflocations, which have relevance to the operations of the WSO. Theseestimates are the basis of the method in which CMs interact to determinewhether they serve WSOs that are capable of interfering with each otherand thus belong to each other's coexistence set.

In accordance with an example embodiment of the invention, when a CMneeds to find out whether a potential coexistence set element which isserved by another CM is really capable of interfering the WSO which theCM serves, the CM determines at least one location relevant for the WSO.The CM transmits to the other CM a request message which contains the atleast one location and identification of the potential coexistence setelement. With the request message the CM asks the other CM to estimatetransmission signal level of the potential coexistence set element inthe at least one given location. In accordance with an exampleembodiment of the invention, the request message also containsidentification of the WSO to which this request is related to (i.e. theWSO which the requesting CM serves) and the frequencies this WSO iscapable of operating at. Additionally, the request message may alsocontain an indication of preferred frequency or frequencies for whichthe other CM provides transmission signal level estimates.

In accordance with an example embodiment of the invention, a CM thatreceives a request message from another CM estimates transmission signallevel of the WSO which the CM serves and which is indicated in therequest and which is the potential coexistence set element in question.Signal level is estimated in the locations indicated in the requestmessage. The CM estimates the signal level in at least one of thefrequencies supported by the potential coexistence set element. If therequest message contains information about frequencies supported by theWSO served by the requesting CM, the CM estimates the signal level in atleast one of the frequencies both the WSOs support. In one embodiment ofthe invention the CM estimates transmission signal level using apreferred transmit signal bandwidth which it may indicate in theresponse message. If the potential coexistence set element is a type ofa single transceiver with a known location, the CM needs to estimateonly the maximum transmission signal level from that transceiver in thelocation(s) indicated in the request. If the potential coexistence setelement is a type of a wireless network which typically comprise ofmultiple transceiver devices, the CM needs to consider transmissionsfrom the devices in the network. One may not know location of all thedevices and if that is the case, the CM should estimate at least somelocations and estimate the maximum transmission signal level fromtransceivers in those locations in the location(s) indicated in therequest. When estimating the locations of the devices in the network,the CM should consider the radio propagation conditions and the radiocharacteristics of the devices in the network. Additionally, the CMshould consider devices at the edge of the network coverage area sincethose devices are possibly closest to the location(s) in the request andthus the sources of the highest transmission signal level in thelocation(s) indicated in the request.

In accordance with an example embodiment of the invention, once the CMwhich received a request message has completed transmission signal levelestimation it may form a response message which contains at least theestimated transmission signal level for each location indicated in therequest. The estimated signal level may be indicated as power density,power or field strength in the given positions. When the level isindicated as power or field strength, one will indicate also the signalbandwidth used in the estimation. Once the response message is ready fortransmission the CM which received the request shall transmit theresponse message to the CM from which the request message was received.

In accordance with an example embodiment of the invention, once therequesting CM (i.e. the CM which transmitted the request message) hasreceived a response message from the other CM indicating estimatedtransmission signal levels in the at least one location, the requestingCM may determine whether the potential coexistence set element iscapable of interfering the WSO which the requesting CM serves and towhich the request was related to.

In accordance with an example embodiment of the invention, a CM that isabout to send a request message to another CM needs to determine atleast one location for which it requests the other CM to estimatetransmission signal levels from the WSO (i.e. potential coexistence setelement) which the other CM serves. The locations should to be such thatthe requesting CM may determine from the estimated transmission signallevels in those locations whether the WSO which the CM serves and towhich this request is related can be interfered by the potentialcoexistence set element.

In accordance with an example embodiment of the invention, if the WSO inquestion is a single transceiver (e.g. fixed type of TVBD as per FCCterms) in one location and the requesting CM may release the WSO'slocation to the other CM in the request, the location indicated in therequest should be the WSO's location. Alternatively, the CM may indicatea set of locations from which one can be the actual location of the WSO.

In accordance with an example embodiment of the invention, if the WSO inquestion is a network like a WLAN basic service set (BSS) managed andoperated by an access point (AP) for which the CM knows just thelocation of the master device (AP and mode II type device as per the FCCterms), the CM needs to provide multiple locations. The locations shouldbe picked up to be such that represent well possible locations ofdevices in the network. The locations indicated in the request shouldcover the location of the master device and the most probable locationsof the slave devices. Additionally, one may consider covering especiallythe locations at the edge of the network since in those locations thetransmission signal level from an alien transmitter is expected to bemost different from the one in the master's location.

FIG. 2A is an example system architecture according to an exampleembodiment of the invention of FIG. 1A, which illustrates the requestingnetwork controller or coexistence manager CM_A, receiving from thecoexistence discovery and information server (CDIS) in FIG. 1A theaddresses of potential neighbor networks and receiving the addresses ofthe neighbor coexistence managers CM_B and CM_C. The requestingcoexistence manager CM_A receives information indicating WSO C2 is acandidate for inclusion in the coexistence set for WSO A1, in an exampleembodiment of the invention.

The figure shows some example steps that the coexistence manager CM_Amay take to accomplish this purpose. In step 202, the coexistencemanager CM_A already knows the identity of the neighbor wirelessnetworks of the wireless network A1, which are the wireless networks B1and C1 in the coexistence set A, since they may interfere with or beinterfered by the transfer wireless network A1. The figure illustratesthe network controller or coexistence manager CM_A, receiving from thecoexistence discovery and information server (CDIS) 107 over theInternet 105 the addresses of potential neighbor coexistence managersthat serve the neighbor wireless networks B1 and C1 in the coexistenceset A, and a candidate C2. The figure shows in step 204, the coexistencemanager CM_A receiving the CM address message 29 reporting the neighborcoexistence managers CM_B and CM_C that serve wireless networks B1, C1,and C2. The figure shows in step 206, the coexistence manager CM_Areceive information indicating WSO C2 is a candidate for inclusion inthe coexistence set for WSO A1, in an example embodiment of theinvention.

FIG. 2B is an example system architecture according to an exampleembodiment of the invention of FIG. 2A, which illustrates the requestingcoexistence manager CM_A is determining at least one location (X,Y)related to WSO A1. The requesting coexistence manager CM_A transmits arequest message to CM_C requesting an estimate of the signal level forat least one location (X,Y) of WSO A1, caused by WSO C2, in an exampleembodiment of the invention.

The figure shows step 207 wherein the requesting coexistence managerCM_A determines at least one location (X,Y) related to WSO A1. In step208, the network controller or coexistence manager CM_A, is transmittinga request to CM_C requesting an estimate of signal level at (X,Y) causedby WSO C2.

In accordance with an example embodiment of the invention, the requestmessage 32 shown in the figure, may include a message type field,indicating it is a coexistence manager to coexistence manager message.The payload of the request message 32 may include a field indicatingthat the message is a request for an estimate of the signal level at thelocation (X,Y) caused by WSO C2. The payload of the request message 32may include a field indicating the request is for WSO A1. The payload ofthe request message 32 may include a field indicating the supportedfrequencies of WSO A1. And, the payload of the request message 32 mayinclude a field indicating preferences for frequencies for signal levelestimation. The requesting coexistence manager may indicate preferencesfor frequencies in which the responding CM performs transmission signallevel estimation. A request message 32 may thus contain preferenceindication information.

FIG. 2C is an example system architecture according to an exampleembodiment of the invention of FIG. 2A, which illustrates the respondingcoexistence manager CM_C responding to the request by estimating thesignal level for at least one location (X,Y) of WSO A1, caused by WSO C2and transmitting a response message to the requesting coexistencemanager, including the estimated signal level for at least one location(X,Y) of WSO A1, caused by WSO C2. The requesting coexistence managerCM_A determines from the estimated signal level, if the WSO C2 is in thecoexistence set of WSO A1. In the example shown, the estimatedtransmission signal level at the at least one location (X,Y) of WSO A1,is sufficiently high to justify including WSO C2 in the coexistence setof WSO A1, in an example embodiment of the invention.

In accordance with an example embodiment of the invention, the responsemessage 34 shown in the figure, may include a message type field,indicating it is a coexistence manager to coexistence manager message.The payload of the response message 34 may include a field indicatingthat the message is a signal level estimate at the location (X,Y) causedby WSO C2. The payload of the response message 34 may include a fieldindicating the response is for WSO A1. The payload of the responsemessage 34 may include a field indicating estimated signal level atfrequencies supported by WSO A1. The payload of the response message 34may include a field indicating the frequencies used in the signal levelestimation. And, the payload of the response message 34 may include afield indicating paired frequency and estimated signal level for aplurality of frequencies, for example FREQ_(—)1/LEVEL_(—)1;FREQ_(—)2/LEVEL_(—)2; FREQ_(—)3/LEVEL_(—)3.

The responding CM needs to decide on which frequency or on whichfrequencies it determines the signal level estimates. If the requestmessage 32 contains frequency preference information, the responding CMmay take that information into account when deciding which frequency orwhich frequencies to use in the estimation.

The responding CM may decide to indicate in the response message 34 thefrequency or the frequencies which were used in the signal levelestimation. The response message 34 may contain one estimate for onefrequency and in case of multiple frequencies the response messagecontains multiple frequency-estimate pairs.

FIG. 3A is an example network diagram of the WSO A1, illustrating thatthe at least one location (X,Y) related to WSO A1 may be the actuallocation, where WSO A1 in is a single transceiver in one location andthe requesting coexistence manager CM_A is permitted to release theWSO's location to another coexistence manager. Alternately, therequesting coexistence manager CM_A may indicate a set of locations, oneof which may be the actual location of the WSO A1, in an exampleembodiment of the invention. In this figure, WSO A1 represents a singletransceiver WSD9, the requesting coexistence manager CM_A needs to findout whether the WSO can be interfered by another WSO that has beenidentified as a potential coexistence set element by CDIS. Therequesting coexistence manager CM_A determines one or more locationsthat represent the WSO. One location (i.e. WSO's actual location) isgiven if the requesting coexistence manager CM_A can release actuallocation of the WSO to the responding coexistence manager CM_C. Multiplelocations are given if the requesting coexistence manager CM_A is notwilling to release actual location of the WSO to the respondingcoexistence manager CM_C. The locations should be selected so that therequesting coexistence manager CM_A can determine from the response thatcontains transmission signal level estimates to the locations, whetherthere is interference to the WSO, which is in this case a singletransceiver.

FIG. 3B is an example network diagram of the WSO A1 as a networkcomprising a master device and slave devices, illustrating that the atleast one location (X,Y) related to WSO A1 may be an average of all ofthe locations of the devices in the network, in an example embodiment ofthe invention. In this figure, WSO A1 represents a network operated by amaster device WSD9 to which a variable number of slave devices,including WSD10, in unknown locations are connected within coverage areof the network. The requesting coexistence manager CM_A needs to findout whether the master device or any of the slave devices can beinterfered by another WSO that has been identified as a potentialcoexistence set element by CDIS. The requesting coexistence manager CM_Adetermines multiple locations that represent the master device andpossible slave devices of the network. The requesting coexistencemanager CM_A needs to estimate coverage area of the network from whichit can estimate possible and probable locations of slave devices.Typically it is enough to indicate locations close to the edge of thecoverage area since transmission powers of this type of WSO is very muchlimited in government regulations and there are no chances to haveinterferers within the coverage area, which are not interfering devicesat the edge. In general, the location should be again selected so thatthe requesting coexistence manager CM_A can determine from the response,which contains transmission signal level estimates to the locations,whether there is interference to the WSO, which is in this case a masterdevice and a set of slave devices.

FIG. 4A is an example network diagram of the WSO C2, illustrating thatWSO C2 in is a single transceiver WSD3 in one location, then theresponding coexistence manager CM_C estimates the signal level for atleast one location (X,Y) of WSO A1, caused by the single transceiverWSD3, in an example embodiment of the invention. The figure shows atransmission signal level estimate in case of a single transceiver WSD3.The responding coexistence manager CM_C needs to estimate maximumtransmission signal level from the WSO C2 it serves and for which it hasreceived a signal level estimation request from the requestingcoexistence manager CM_A. The requesting coexistence manager CM_Aconsiders this WSO C2 as a potential coexistence set element for WSO A1that the requesting coexistence manager CM_A serves, and requests thisresponding coexistence manager CM_C to estimate what is maximumtransmission signal level from the WSO C2 that the respondingcoexistence manager CM_C serves, to a set of locations representing WSOA1. Since the WSO C2, in this case, is a single transceiver WSD3 with aknown location, the responding coexistence manager CM_C needs to merelyestimate maximum signal level of transmission from WSD3 as it wouldaffect a set of locations representing WSO A1 indicated in the request.The responding coexistence manager CM_C may use any type and kind ofpropagation model it has to estimate the signal levels. The morerealistic model it has available the more accurate the estimation.

FIG. 4B is an example network diagram of the WSO C2, illustrating thatWSO C2 in is a network comprising a master device WSD3 and several slavedevices including slave device WSD4, then the responding coexistencemanager CM_C estimates the signal level for at least one location (X,Y)of WSO A1, caused by each of the devices in the network of WSO C2, in anexample embodiment of the invention. The figure shows transmissionsignal level estimate in the case of WSO C2 as a network. The respondingcoexistence manager CM_C needs to estimate transmission signal levelsfrom the WSO C2 it serves and for which it has received a signal levelestimation request from requesting coexistence manager CM_A. Therequesting coexistence manager CM_A considers this WSO C2 as a potentialcoexistence set element for WSO A1 that the requesting coexistencemanager CM_A serves and requests the responding coexistence manager CM_Cto estimate what is maximum transmission signal level from the WSO C2that responding coexistence manager CM_C serves, to a set of locationsrepresenting WSO A1. Since the WSO C2, in this case, is a networkoperated by a master device WSD3 with a known location and a variablenumber of slave devices, including WSD4, the responding coexistencemanager CM_C needs to estimate what is the maximum signal level oftransmission from any device in the network of WSO C2. If the locationof the slave devices is unknown, responding coexistence manager CM_Cfirst estimates the locations and subsequently estimates maximum signallevels from devices in those estimated locations in the locations in WSOA1 indicated in the request. If slave locations are known, no locationestimate is needed, and the responding coexistence manager CM_C mayproceed directly to the signal level estimation. The respondingcoexistence manager CM_C estimates the maximum transmission signal levelfor each location in WSO A1 indicated in the request from each device(estimated or actual one) in the WSO C2 network and indicates thehighest level for each indicated location in WSO A1. The respondingcoexistence manager CM_C may use any type and kind of propagation modelit has to estimate the signal levels. The more realistic model it hasavailable the more accurate the estimation.

FIG. 5 is a non-limiting example frequency band diagram illustrating anexample TDMA coexistence frame sub-band 28 in the TV band white spacelocally unused by licensed TV broadcasters in the 174-204 MHz band,representing broadcast TV channels 7, 8, 9, 10, and 11 in the Richmond,Va. (USA) area, as shown in FIG. 6, according to an embodiment of thepresent invention. License-exempt access to these bands as a secondaryuse for coexistence of networks requesting additional resources, mayinclude restrictions on geographic location, transmission power, range,and bandwidth of the transmissions of the requesting networks, in anexample embodiment of the invention.

As a non-limiting example, the 802.11 WLAN standards specify frequenciesfor operation in the 2.400-2.500 GHz ISM band, the 5 GHz ISM band, andthe IEEE 802.11 ad Very High Throughput 60 GHz band. The 802.11 WLANstandards specify an OFDM-based physical layer with a bandwidth of 20MHz channel separation. At 11 MHz from the center of the channel, theenergy is approximately 20 dB lower than the maximum signal level.Further away from the center frequency, the energy levels fall furtherresulting in minimal interference on adjacent channels. The TV bandwhite spaces at 54-88 MHz and at 470-806 MHz are good candidates forcoexistence of an 802.11 WLAN wireless LAN channel. The earthstation-to-satellite white space spectrum at 2.025 GHz to 2.110 GHz is agood candidate for coexistence of an 802.11 WLAN wireless LAN channel. ATV band white space locally unused by licensed TV broadcasters, forexample, in the 174-204 MHz band, representing the local absence ofbroadcast TV channels 7, 8, 9, 10, and 11, as is the circumstance in theRichmond, Va. (USA) area, is a good candidate for coexistence of an802.11 WLAN wireless LAN channel.

FIG. 5 shows a non-limiting example of the location of the white spacesin the RF spectrum and example TDMA coexistence frames in the whitespace spectrum, showing the freely available time slots before anynetworks have been allocated slots. The white spaces include the FCCdedicated TV white space 54-88 MHz band, the FCC dedicated TV whitespace 470-806 MHz band, and locally unused the earthstation-to-satellite white space spectrum in 2.025 GHz to 2.110 GHz.

In an example embodiment of the invention, there are a number of TVWScoexistence techniques possible for enabling two or more independentlyoperated wireless networks or devices using different radio technologiesadapted for TV white space frequency bands, to access the same TV whitespace frequency band in the same location without mutual interference.Some examples of coexistence techniques include dynamic frequencyselection, transmit power control, listen-before-talk behavior, timedivision multiplexing different IEEE 802 technologies, message-basedon-demand spectrum contention, and control through a centralized networkcontroller or coexistence manager.

FIG. 6 shows an example map of the Richmond, Va. (USA) geographic areaand an overlay of coverage areas for broadcast TV channels 7, 8, 9, 10,and 11, illustrating that there is a locally available TV band whitespace that is unused by licensed TV broadcasters in the 174-204 MHzband, as shown in FIG. 5. The cities where there are TV broadcasters forTV channels 7, 8, 9, 10, and 11 in a circular area of approximately 160kilometers in diameter surrounding the city of Richmond, Va., are shownin the following table. The map of FIG. 6 shows that there is nocoverage by licensed TV broadcasters in the 174-204 MHz band, which istherefore a locally available TV band white space.

WASHINGTON, DC TV CHANNEL 7 174-180 MHz NORFOLK, VIRGINIA TV CHANNEL 7174-180 MHz HARRISONBURG, VA TV CHANNEL 8 180-186 MHz WASHINGTON, DC TVCHANNEL 9 186-192 MHz NORFOLK, VIRGINIA TV CHANNEL 9 186-192 MHzWINCHESTER, VA TV CHANNEL 10 192-198 MHz RALEIGH, NC TV CHANNEL 11198-204 MHz STAUNTON, VIRGINIA TV CHANNEL 11 198-204 MHz

FIG. 7A is a functional block diagram according to an example embodimentof the invention, illustrating an example master WSD9 device includingthe control node or coexistence enabler 118 for the wireless device. Thedevice may be configured to operate in the TVWS coexistence bands oradditional RF spectrum bands where there may be no primary user radiosoperating in the neighboring wireless networks, in an example embodimentof the invention.

In an example embodiment of the invention, master WSD9 includes aprotocol stack, including the radio 128 and the IEEE 802.11 MAC 142,which may be based, for example, on the IEEE 802.11 WLAN standard. TheMAC 142 includes integrated TV white space features. The protocol stackmay also include a network layer 140, a transport layer 138, and anapplication program 136. The example master WSD9 may include a processor134 that includes a dual or multi core central processing unit CPU_(—)1and CPU_(—)2, a RAM memory, a ROM memory, and an interface for a keypad,display, and other input/output devices. A location sensor 132, such asa GPS may be included to establish the geographic location of the masterWSD9, and the location of the master WSD9 is reported to the networkcontroller or coexistence manager CM_A. The coexistence enabler 118 maysend resource requests to the coexistence manager CM_A. The MAC 142includes integrated TV white space features to communicate using theradio 128 in channels in the TV white spaces band reallocated by thecoexistence manager CM_A, without mutual interference. The spectrumsensor 130 senses the electromagnetic environment of the master WSD9 andreports it to the coexistence manager CM_A.

In an example embodiment of the invention, the geo-location database 200of FIG. 7C, may communicate the allowed emission levels via the Internet105 to the coexistence manager CM_A, which forwards the allowed emissionlevels via the Internet 105 to coexistence enabler 118 in the masterWSD9.

In an example embodiment of the invention, the master WSD9 includesspectral decoding logic 133. When input data are not properlycorrelated, a rectangularly-pulsed OFDM signal is discontinuous in phaseand thus exhibits large power spectral sidelobes decaying asymptoticallyas the frequency. Such large sidelobes cause strong interference toadjacent channels and need to be suppressed before transmission.Spectral precoding is capable of suppressing sidelobe powers effectivelywithout trading off system error performance or implementationcomplexity. By spectral precoding, significant sidelobe suppression isachieved by precoding data symbols in frequency domain without resort tospecific data values. The idea is to introduce correlation among datasymbols by a fixed precoder matrix in a way that the spectrally-precodedrectangularly-pulsed OFDM signal exhibits extremely small power spectralsidelobes decaying asymptotically, and thereby high spectral efficiency.Spectral precoders are all invertible and thus enable realizabledecoding at the receiver while providing good system error performance.An example spectral decoder is described in the publication by Char-DirChung, “Spectral Precoding for Constant-Envelope OFDM”, IEEETransactions on Communications, vol. 58, no. 2, February 2010, pages555-567.

In an example embodiment of the invention, the interface circuits inFIG. 7A may interface with one or more radio transceivers, battery andother power sources, key pad, touch screen, display, microphone,speakers, ear pieces, camera or other imaging devices, etc. The RAM andROM may be removable memory devices such as smart cards, subscriberidentity modules (SIMs), wireless identification modules (WIMs),semiconductor memories such as RAM, ROM, PROMS, flash memory devices,etc. as shown in FIG. 10. The processor protocol stack layers, and/orapplication program may be embodied as program logic stored in the RAMand/or ROM in the form of sequences of programmed instructions which,when executed in the CPU, carry out the functions of exampleembodiments. The program logic may be delivered to the writeable RAM,PROMS, flash memory devices, etc. of the control node or coexistenceenabler and coexistence manager from a computer program product orarticle of manufacture in the form of computer-usable media such asresident memory devices, smart cards or other removable memory devices.Alternately, they may be embodied as integrated circuit logic in theform of programmed logic arrays or custom designed application specificintegrated circuits (ASIC). The one or more radios in the device may beseparate transceiver circuits or alternately, the one or more radios maybe a single RF module capable of handling one or multiple channels in ahigh speed, time and frequency multiplexed manner in response to theprocessor.

In an example embodiment of the invention, the master WSD9 of FIG. 7Aincludes processor 134 that may access random access memory RAM and/orread only memory ROM in order to obtain stored program code and data foruse during processing. The RAM or ROM may generally include removable orimbedded memories that operate in a static or dynamic mode. Further, theRAM or ROM may include rewritable memories such as Flash, EPROM, EEPROM,etc. Examples of removable storage media based on magnetic, electronicand/or optical technologies such as magnetic disks, optical disks,semiconductor memory circuit devices and micro-SD memory cards (SDrefers to the Secure Digital standard) are shown at 126 and in FIG. 10,and may serve, for instance, as a data input/output means. Code mayinclude any interpreted or compiled computer language includingcomputer-executable instructions. The code and/or data may be used tocreate software modules such as operating systems, communicationutilities, user interfaces, more specialized program modules, etc.

FIG. 7B is a functional block diagram according to an example embodimentof the invention, illustrating an example slave WSD10 device. The devicemay be configured to operate in the TVWS coexistence bands or additionalRF spectrum bands there may be no primary user radios operating in theneighboring wireless networks, in an example embodiment of theinvention.

In an example embodiment of the invention, slave WSD10 includes aprotocol stack, including the radio 128 and the IEEE 802.11 MAC 142,which may be based, for example, on the IEEE 802.11 WLAN standard. TheMAC 142 includes integrated TV white space features. The protocol stackmay also include a network layer 140, a transport layer 138, and anapplication program 136. The example slave WSD10 may include a processor134 that includes a dual or multi core central processing unit CPU_(—)1and CPU_(—)2, a RAM memory, a ROM memory, and an interface for a keypad,display, and other input/output devices. A location sensor 134, such asa GPS may be included to establish the geographic location of the slaveWSD10, and the location of the slave WSD10 is reported to the networkcontroller or coexistence manager CM_A. The MAC 142 includes integratedTV white space features to communicate using the radio 128 in channelsin the TV white spaces band reallocated by the coexistence manager CM_A,without mutual interference. The spectrum sensor 130 senses theelectromagnetic environment of the slave WSD10 and reports it to themaster WSD10 that may provide the reports to the coexistence enabler forfurther processing and delivery to the coexistence manager CM_A.

In an example embodiment of the invention, the geo-location database 200may communicate the allowed emission levels via the Internet 105 to thecoexistence manager CM_A, which forwards the allowed emission levels tothe slave WSD10 via the coexistence enabler 118 in the master WSD9 andthe master WSD9 itself.

In an example embodiment of the invention, the interface circuits inFIG. 7B may interface with one or more radio transceivers, battery andother power sources, key pad, touch screen, display, microphone,speakers, ear pieces, camera or other imaging devices, etc. The RAM andROM may be removable memory devices such as smart cards, SIMs, WIMs,semiconductor memories such as RAM, ROM, PROMS, flash memory devices,etc., as shown in FIG. 10. The processor protocol stack layers, and/orapplication program may be embodied as program logic stored in the RAMand/or ROM in the form of sequences of programmed instructions which,when executed in the CPU, carry out the functions of exampleembodiments. The program logic may be delivered to the writeable RAM,PROMS, flash memory devices, etc. of the control node or coexistenceenabler and coexistence manager from a computer program product orarticle of manufacture in the form of computer-usable media such asresident memory devices, smart cards or other removable memory devices.Alternately, they may be embodied as integrated circuit logic in theform of programmed logic arrays or custom designed application specificintegrated circuits (ASIC). The one or more radios in the device may beseparate transceiver circuits or alternately, the one or more radios maybe a single RF module capable of handling one or multiple channels in ahigh speed, time and frequency multiplexed manner in response to theprocessor.

In an example embodiment of the invention, the slave WSD10 of FIG. 7Bincludes processor 134 that may access random access memory RAM and/orread only memory ROM in order to obtain stored program code and data foruse during processing. The RAM or ROM may generally include removable orimbedded memories that operate in a static or dynamic mode. Further, theRAM or ROM may include rewritable memories such as Flash, EPROM, EEPROM,etc. Examples of removable storage media based on magnetic, electronicand/or optical technologies such as magnetic disks, optical disks,semiconductor memory circuit devices and micro-SD memory cards are shownat 126 and in FIG. 10, and may serve, for instance, as a datainput/output means. Code may include any interpreted or compiledcomputer language including computer-executable instructions. The codeand/or data may be used to create software modules such as operatingsystems, communication utilities, user interfaces, more specializedprogram modules, etc.

FIG. 7C is an example network diagram according to an embodiment of thepresent invention, illustrating the control node or coexistence enabler118, communicating over a backhaul wireline and/or internet link withthe network controller or coexistence manager CM_A, in an exampleembodiment of the invention. The coexistence manager CM_A maycommunicate over the internet 105 with the geo-location database 200 andthe coexistence network element coexistence discovery and Informationserver (CDIS) 107, in an example embodiment of the invention.

In an example embodiment of the invention, the master WSD, such as WSD9,may send queries for the available spectrum to a geo-location database200. Database 200 may comprise some internal structure, for example, inform functional blocks such as processors, memory, software/hardwaremodules, and the like, for performing operations described herein. Suchblocks may for example transmit and receive information such as spectruminformation, emission characteristics, and/or allowed operatingparameters. The master WSD9 uses the IEEE 802.11 wireless LAN (WLAN)protocol for is normal communications on its IEEE 802.11 links, but itis capable of communicating in white space spectrum on TVWS links 2, 3,and 4. The returned information from the geo-location database 200enables the operation in the white space spectrum, of both the masterWSD9 and its associated slave WSD10 that is within the master WSD9'soperational area. There may be other reasons to use TVWS, such as betterpropagation. Normal communication medium typically is available for WLAN(e.g. 2.4 or 5 GHz), but TVWS may not be available everywhere dueprimary users.

FIG. 8A is an example flow diagram 600 of operational steps inrequesting coexistence manager CM_A, according to an embodiment of thepresent invention. The steps of the flow diagram 600 of FIG. 8A mayrepresent computer code instructions stored in the RAM and/or ROM memoryof the master white space device, which when executed by the centralprocessing units (CPU), carry out the functions of an example embodimentof the invention. The steps may be carried out in another order thanshown and individual steps may be combined or separated into componentsteps.

Step 602: receiving, by a coexistence manager, information indicatingthat a candidate wireless network served by another coexistence managermay interfere with a wireless network served by the coexistence manager;

Step 604: determining, by the coexistence manager, at least one locationrelated to the wireless network served by the coexistence manager;

Step 606: transmitting, by the coexistence manager, a request message tothe other coexistence manager, indicating the at least the one locationand requesting an estimate of a transmission signal level at the atleast one location caused by the candidate wireless network;

Step 608: receiving, by the coexistence manager, from the othercoexistence manager, a response message including information indicatingan estimated transmission signal level at the at least one locationcaused by the candidate wireless network; and

Step 610: determining, by the coexistence manager, whether the candidatewireless network interferes with the wireless network served by thecoexistence manager based on the received estimated transmission signallevel at the at least one location.

FIG. 8B is an example flow diagram 650 of operational steps inresponding coexistence manager CM_C, according to an embodiment of thepresent invention. The steps of the flow diagram 600 of FIG. 8B mayrepresent computer code instructions stored in the RAM and/or ROM memoryof the master white space device, which when executed by the centralprocessing units (CPU), carry out the functions of an example embodimentof the invention. The steps may be carried out in another order thanshown and individual steps may be combined or separated into componentsteps.

Step 652: receiving, by a coexistence manager, a request message fromanother coexistence manager, indicating at least one location related toanother wireless network served by the other coexistence manager andrequesting an estimate of a transmission signal level at the at leastone location related to the other wireless network, caused by acandidate wireless network served by the coexistence manager;

Step 654: estimating, by the coexistence manager, a transmission signallevel at the at least one location related to the other wirelessnetwork, caused by the candidate wireless network; and

Step 656: transmitting, by the coexistence manager, a response messageincluding information indicating the estimated transmission signal levelat the at least one location.

FIG. 9 is an example frequency band diagram illustrating an example TDMAcoexistence frame 24′ in sub-band 14′ in an unpaired time domain duplexfrequency white space of 900 to 905 MHz in the uplink portion of amobile device communications frequency band, according to an exampleembodiment of the invention. FIG. 9 illustrates an example frequencyplan for the example mobile device frequency band, with an uplinkportion between 890 and 915 MHz and a down link portion between 935 and960 MHz, similar to a portion of the frequency plan for GSM. In theexample frequency plan shown in FIG. 9, a 5 MHz band between 945 and 950MHz in the down link portion is reserved for other uses, for example asan emergency services band. Since the time domain duplex operation ofthe mobile device system requires matched uplink frequencies to theallocated down link frequencies, there is an unpaired band between 900and 905 MHz in the uplink portion. In accordance with an exampleembodiment of the invention, the unpaired band between 900 and 905 MHzis used as a coexistence band. FIG. 9 shows an example TDMA coexistenceframe 24′ in sub-band 14′ in the unpaired time domain duplex frequencywhite space 36 in the uplink portion of the mobile device frequencyband, which may be used by a cellular telephone base station masterdevice and the cellular telephone slave devices.

In an example embodiment of the invention, a master WSD device and itsassociated slave WSD device in the master device's operation area, mayuse a cellular 3rd Generation Partnership Project (3GPP) standard. Acellular 3rd Generation Partnership Project (3GPP) standard, may includeThird-Generation (3G), Wideband Code Division Multiple Access (W-CDMA),High Speed Packet Access (HSPA), Long Term Evolution (LTE), LTE Advanced(LTE-A), or International Mobile Telecommunications Advanced (IMT-A).The master WSD device and its associated slave WSD device in the masterdevice's operation area, may use any of these standards for their normalcommunications on the cell links, but they are capable of communicatingin white space spectrum on TVWS links 6, 7, and 8. The returnedinformation from the geo-location database enables the operation in thewhite space spectrum, of both the master WSD and its associated slaveWSD that are within the master WSD's operational area. FIG. 9 shows anexample TDMA coexistence frame 24′ in sub-band 14′ in the unpaired timedomain duplex frequency white space 36 in the uplink portion of themobile device frequency band, which may be used by the cell base masterdevice WSD and the cell slave device WSD. TVWS may be used, for examine,in carrier aggregation, where it is available, in addition to licensedmedia. Similar examples include local area technologies implemented forexample, cellular technologies for small cell operations such ashotspots, pico cells, femto cells, home nodes such as Home Node B (HNB),Home eNodeB (HeNB) and the like. Further, integrated local nodes ofsecondary networks may consist of 3GPP technologies combined with theIEEE technologies, for example LTE Home eNodeB (LTE HeNB) with Wi-Fi.

FIG. 10 illustrates an example embodiment of the invention, whereinexamples of removable storage media 126 are shown, based on magnetic,electronic and/or optical technologies, such as magnetic disks, opticaldisks, semiconductor memory circuit devices and micro-SD memory cards(SD refers to the Secure Digital standard), for storing data and/orcomputer program code as an example computer program product, inaccordance with at least one embodiment of the present invention.

Using the description provided herein, the embodiments may beimplemented as a machine, process, or article of manufacture by usingstandard programming and/or engineering techniques to produceprogramming software, firmware, hardware or any combination thereof.

Any resulting program(s), having computer-readable program code, may beembodied on one or more non-transitory computer-usable media such asresident memory devices, smart cards or other removable memory devices,or transmitting devices, thereby making a computer program product orarticle of manufacture according to the embodiments. As such, the terms“article of manufacture” and “computer program product” as used hereinare intended to encompass a computer program that exists permanently ortemporarily on any computer-usable medium.

As indicated above, memory/storage devices include, but are not limitedto, disks, optical disks, removable memory devices such as smart cards,SIMs, WIMs, semiconductor memories such as RAM, ROM, PROMS, etc.Transmitting mediums include, but are not limited to, transmissions viawireless communication networks, the Internet, intranets,phone/modem-based network communication, hard-wired/cabled communicationnetwork, satellite communication, and other stationary or mobile networksystems/communication links.

Although specific example embodiments have been disclosed, a personskilled in the art will understand that changes can be made to thespecific example embodiments without departing from the spirit and scopeof the invention.

1. A method, comprising: receiving, by a coexistence manager,information indicating that a candidate wireless network served byanother coexistence manager may interfere with a wireless network servedby the coexistence manager; determining, by the coexistence manager, atleast one location related to the wireless network served by thecoexistence manager; transmitting, by the coexistence manager, a requestmessage to the other coexistence manager, indicating the at least theone location and requesting an estimate of a transmission signal levelat the at least one location caused by the candidate wireless network;receiving, by the coexistence manager, from the other coexistencemanager, a response message including information indicating anestimated transmission signal level at the at least one location causedby the candidate wireless network; and determining, by the coexistencemanager, whether the candidate wireless network interferes with thewireless network served by the coexistence manager based on the receivedestimated transmission signal level at the at least one location.
 2. Themethod of claim 1, wherein the information indicating that the candidatewireless network may interfere with the wireless network served by thecoexistence manager is received from a coexistence discovery andinformation server.
 3. The method of claim 1, further comprising:performing, by the coexistence manager, calculations using the receivedestimated transmission signal level, to estimate an effect of thereceived estimated transmission signal level on the wireless networkserved by the coexistence manager; and determining, by the coexistencemanager, to include the candidate wireless network in a coexistence setbased on the performed calculations.
 4. The method of claim 1, whereinthe at least one location related to the wireless network served by thecoexistence manager, is one of actual location or estimated location ofone or more apparatuses belonging to the wireless network.
 5. The methodof claim 1, wherein the request message includes at least one of anidentification of the wireless network served by the coexistencemanager, and frequencies at which the wireless network served by thecoexistence manager, is capable of operating.
 6. The method of claim 1,wherein locations indicated in the request cover locations of a masterdevice and most probable locations of slave devices in the wirelessnetwork served by the coexistence manager.
 7. An apparatus, comprising:at least one processor; at least one memory including computer programcode; the at least one memory and the computer program code configuredto, with the at least one processor, cause the apparatus at least to:receive information indicating that a candidate wireless network servedby another coexistence manager may interfere with a wireless networkserved by the apparatus; determine at least one location related to thewireless network served by the apparatus; transmit a request message tothe other coexistence manager, indicating the at least the one locationand requesting an estimate of a transmission signal level at the atleast one location caused by the candidate wireless network; receivefrom the other coexistence manager, a response message includinginformation indicating an estimated transmission signal level at the atleast one location caused by the candidate wireless network; anddetermine whether the candidate wireless network interferes with thewireless network served by the apparatus, based on the receivedestimated transmission signal level at the at least one location.
 8. Theapparatus of claim 7, wherein the information indicating that thecandidate wireless network may interfere with the wireless networkserved by the coexistence manager is received from a coexistencediscovery and information server.
 9. The apparatus of claim 7, furthercomprising: the at least one memory and the computer program codeconfigured to, with the at least one processor, cause the apparatus atleast to: perform calculations using the received estimated transmissionsignal level, to estimate an effect of the received estimatedtransmission signal level on the wireless network served by thecoexistence manager; and determine to include the candidate wirelessnetwork in a coexistence set based on the performed calculations. 10.The apparatus of claim 7, wherein the at least one location related tothe wireless network served by the coexistence manager, is one of actuallocation or estimated location of one or more apparatuses belonging tothe wireless network.
 11. The apparatus of claim 7, wherein the requestmessage includes at least one of an identification of the wirelessnetwork served by the coexistence manager, and frequencies at which thewireless network served by the coexistence manager, is capable ofoperating.
 12. The apparatus of claim 7, wherein locations indicated inthe request cover locations of a master device and most probablelocations of slave devices in the wireless network served by thecoexistence manager.
 13. A computer program product comprising computerexecutable program code recorded on a computer readable, non-transitorystorage medium, the computer executable program code comprising: codefor receiving, by a coexistence manager, information indicating that acandidate wireless network served by another coexistence manager mayinterfere with a wireless network served by the coexistence manager;code for determining, by the coexistence manager, at least one locationrelated to the wireless network served by the coexistence manager; codefor transmitting, by the coexistence manager, a request message to theother coexistence manager, indicating the at least the one location andrequesting an estimate of a transmission signal level at the at leastone location caused by the candidate wireless network; code forreceiving, by the coexistence manager, from the other coexistencemanager, a response message including information indicating anestimated transmission signal level at the at least one location causedby the candidate wireless network; and code for determining, by thecoexistence manager, whether the candidate wireless network interfereswith the wireless network served by the coexistence manager based on thereceived estimated transmission signal level at the at least onelocation.
 14. A method, comprising: receiving, by a coexistence manager,a request message from another coexistence manager, indicating at leastone location related to another wireless network served by the othercoexistence manager and requesting an estimate of a transmission signallevel at the at least one location, caused by a candidate wirelessnetwork served by the coexistence manager; estimating, by thecoexistence manager, a transmission signal level at the at least onelocation, caused by the candidate wireless network served by thecoexistence manager; and transmitting, by the coexistence manager, aresponse message including information indicating the estimatedtransmission signal level at the at least one location.
 15. The methodof claim 14, wherein the request message includes one or more offrequencies at which the coexistence manager is requested to estimatethe transmission signal level.
 16. An apparatus, comprising: at leastone processor; at least one memory including computer program code; theat least one memory and the computer program code configured to, withthe at least one processor, cause the apparatus at least to: receive arequest message from another coexistence manager, indicating at leastone location related to another wireless network served by the othercoexistence manager and requesting an estimate of a transmission signallevel at the at least one location related to the other wirelessnetwork, caused by a candidate wireless network served by the apparatus;estimate a transmission signal level at the at least one locationrelated to the other wireless network, caused by the candidate wirelessnetwork; and transmit a response message including informationindicating the estimated transmission signal level at the at least onelocation.
 17. The apparatus of claim 16, wherein the request messageincludes one or more of frequencies at which the coexistence manager isrequested to estimate the transmission signal level.
 18. A computerprogram product comprising computer executable program code recorded ona computer readable, non-transitory storage medium, the computerexecutable program code comprising: code for receiving, by a coexistencemanager, a request message from another coexistence manager, indicatingat least one location related to another wireless network served by theother coexistence manager and requesting an estimate of a transmissionsignal level at the at least one location related to the other wirelessnetwork, caused by a candidate wireless network served by thecoexistence manager; code for estimating, by the coexistence manager, atransmission signal level at the at least one location related to theother wireless network, caused by the candidate wireless network; andcode for transmitting, by the coexistence manager, a response messageincluding information indicating the estimated transmission signal levelat the at least one location.